Temperature dependence of band gaps in HgCdTe and other semiconductors

Band-edge shifts induced by the electron-phonon interaction are calculated for HgCdTe alloys and various semiconductor compounds starting from accurate zero-temperature band structures. The calculated temperature variation of gaps agrees with experiments to better than 10% in all materials except InAs and InSb where the deviation is about 50%. While the simple picture that the intra (inter)-band transitions reduce (increase) the gap still holds, we show that both the conduction band edge E_c and valence band edge E_v move down in energy. These shifts in E_v affect the valence band offsets in heterojunctions at finite temperature. The temperature variations of valence band offset and the electron effective mass are also reported.